#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
int main()
{
	char c[205];
	char tmp;
	scanf("%s", c);
	int len = strlen(c);
	for (int i = 1; i < len - 1; i++)
	{
		for (int j = i; j < len - 1; j++)
		{
			if (c[i] < c[j])
			{
				tmp = c[i];
				c[i] = c[j];
				c[j] = tmp;
			}
		}
	}
	printf("%s", c);
	return 0;
}
